Window blinds having a plurality of equally spaced, parallel, horizontal slats are well-known and are oftentimes referred to as venetian blinds. In these conventional blinds, the individual slats are supported by a pair of ladder tapes having cross-members, sometimes referred to as ladder cords, extending therebetween. In addition, lift cords extend down from a headrail, or valance, through holes in the center of each slat, to a bottom rail. The lift cords are used to adjust the height of the window blind.
There are a number of disadvantages in these conventional window blinds. The use of ladder cords to support the slats unduly increases the stack height of the window blind when the blind is raised to its uppermost position. A small stack height is desirable to maximize the open area of a window when the blind is raised to its uppermost position. The use of ladder cords also hinders the complete tilting and, thus, complete closure of the slats. By routing the lift cords through holes in the slats, privacy is limited because, like the ladder cords, the lift cords hinder the complete tilting and thus, complete closure of the slats as well. In addition, even when the slats are closed, some light can still pass through the slats because of the holes. Finally, with the lift cords passing through each slat, the individual slats cannot be removed from the blind for cleaning, repair or replacement.
U.S. Pat. No. 3,916,973 discloses a blind assembly employing braided tilt cords which extend on the outside of the slats. Flexible loop-shaped attachments extend out of the cord and connect to securing devices on the slats. However, this device also employs a central opening in the slat for a pull cord. As such, this device does not allow for removal of the slats.
Other blinds have been designed having removable slats for cleaning and repair. For example, U.S. Pat. No. 3,086,586 discloses a blind with slats having contoured slots. Upon assembly, the lift cords are inserted into the slats via the contoured slots. To remove the slat from the blind, the lift cords are simply removed from the slat via the contoured slots. U.S. Pat. No. 2,662,593 discloses a blind that eliminates slots in the slats but adds notches on the sides of the slats in order to attach a rigid wire clip to the slats. The rigid wire clip is required to retain the slats to the ladder cords. U.S. Pat. No. 2,532,617 also discloses a blind that eliminates slots in the slats. This blind, however, employs ladder cords and compound clips to retain the slats to the ladder cords. Although these blinds allow for slat removal, the blinds still suffer from increased stack height, incomplete closure of the slats, and light passage through the holes, or slots in the slats. Furthermore, these blinds are complex and costly.